Method for repairing old sonar transducers

ABSTRACT

The method of using a stiff non-melting silicone lubricant; namely, Di-Methyl Polysiloxane oil and Silicone Oxide (SiO2) compound to repair and seal sonar transducers. The method of repairing the old transducers comprises the steps of using a chisel shaped hot iron to remove the rubber facing of the transducer resonator, filling the cavity with a non-melting silicone lubricant, specifically Di-Methyl Polysiloxane oil and Silicone Oxide (SiO2) compounds, then encasing the transducer with an exterior boot.

United States Patent [1 1 Norfleet et al.

[ Oct. 23, 1973 METHOD FOR REPAIRING OLD SONAR TRANSDUCERS Inventors:William V. Norileet, 2313 Main St., Napa; Wilmer Charles Sibbach, 925 N.Camino Alta, Vallejo; Donald R. Schueler, 3064 Linda Vista, Napa, all ofCalif.

Filed: Oct. 8, 1970 Appl. N0.: 79,151

U.S. Cl 29/401, 29/594, 340/8 LF Int. Cl B22d 19/10, B23p 7/00 Field ofSearch 29/401, 594;

References Cited UNITED STATES PATENTS 4/1948 Mason 340/8 LF 10/1951Kroft et al 340/8 LF STEPS STRIP ELEMENT FACE PLATE 1 WITH CHISEL CLEANEXPOSED II RADIATING SURFACE WITH WIRE BRUSH MANUAL APPLICATION OFCOMPOUND 111 TO TRANSDUCER FACE INSTALL N DRY BOOT APPLY VACUUM OF Y.27" FOR 24 HRS. TO. sEcuRE BOOT PLACE BANDS ON TOP AND BOTTOM OF BOOT AREDUCE VAC ('--'6in) m1 TO OPERATIONAL LEVEL OF TRANSDUCER 2,613,26110/1952 Massa 340/10 2,977,573 3/l96l Mott 3,281,769 10/1966 Hueter340/10 X Primary Examiner-John F. Campbell Assistant ExaminerDonald C.Reiley, lll AttorneyR. S. Sciascia and Charles D. B. Curry [57] ABSTRACTThe method of using a stiff non-melting silicone lubricant; namely,Di-Methyl Polysiloxane oil and Silicone Oxide (SiO2) compound to repairand seal sonar transducers. The method of repairing the old transducerscomprises the steps of using a chisel shaped hot iron to remove therubber facing of the transducer resonator, filling the cavity with anon-melting silicone lubricant, specifically Di-Methyl Polysiloxane oiland Silicone Oxide (SiO2) compounds, then encasing the transducer withan exterior boot.

5 Claims, 5 Drawing Figures APPLY INSTALL COMPOUND BOOT WET in TO BOOTPATENIE0ucI23|97a 3.766330 SHEET 1 UF 2 INVENTORS WILLIAM V. NORFLEETWILMER C. SIBBACH DONALD R. SCHUELER w wa /4 ATTORNEY- PATENTEB BT2 973.766.630

- sum 2 0 2 STEPS 9 SF' EE sTR|P ELEMENT mwE- I AC PLATE WITH ii 2nCHISEL r/,'

:/-;2; l2 T TfT/T/P ,1

. ??fl CLEAN EXPOSED /w B 11 RADIATING SURFACE kw WITH WIRE BRUSH z?MANUAL APPLICATION 1 OF COMPOUND m w o TRANSDUCER FACE y FIG 3 E AINSTALL DZ DRY BOOT Nb APPLY gggq- COMPOUND 111 TO BOOT APPLY VACUUM OFY 27-" FOR 24 HRS. o SECURE BOOT P AcE BANDS ON It A TOP AND BOTTOM OFBOOT F IG 4 REDUCE VAC ('-=-'6in) INVENTORS ATTORNEY BACKGROUND OF THEINVENTION The present invention relates generally to the use of a stiffnon-melting silicone lubricant with high energy transfer couplingcharacteristics as an energy transfer coupling and more particularly toa new method of using'a specificsilicone lubricant; specifically, a Di-Methyl Polysiloxane oil and Silicone Oxide (SiO2) compound sold underthe trade-name Dow Corning l l 1 Compound (DC-1 1 1); as a repairmaterial and seal for sonar transducers. i

Prior methods employed the use of castor oil as an energy transfercoupling, and a seal for retaining the castor oil. Castor oil beinghighly hygroscopic in nature, absorbs moisture from the atmosphereduring application, so that when the repaired transducer is placed online, and driven at high levels of power, a mismatch would developbetween the rubber boot and the transducer. This mismatch causescavitation in the rubber faces; with a subsequent reduction of power,and efficiency in the transducer. It has been found that cavitationcreates most of the problems which eventually cause complete transducerfailure or at least a reduction in efficiency to an unsatisfactorylevel. In addition to being hygroscopic, castor oil has a high viscosityand thus does not remain in the area of application, so that a specialretainer means was required. Additionally, castor oil will leak intotransducer interiors, penetrate wiring harnesses, and eventually reducethe overall resistance to ground in the transducer. Moreover, when thecastor oil seeps into the bottom of the transducer, the seepage createsadditional dry areas between the element faces and the rubber boot,causing somewhat irregular power output patterns. Finally, in the oldprocess, the cavitated and oil soaked elements had to be electricallydisconnected, removed, and replaced with new elements. This made theprevious method of repair more time consuming as well as very costly.

SUMMARY OF THE INVENTION The new improved method will overcome theperplexities caused by the use of castor oil. It has been found that theuse of Di-Methyl Polysiloxane oil Silicone Oxide (SiO2) (DC-111)provides an excellent coupling over the entire surface of the transducerwhereas castor oil fails to provide ev'en the minimumcouplingcharacteristics desired. 7

The consistence of Di-Me'thyl Polysiloxane oil silicone oxide (SiO2)compound hereafter referred to as DC-lll eliminates seepage andresultant dry spots. The consistency of DC-lll also eliminates thecontamination of the exterior of the transducer which in turn reducesthe overall resistance to ground. It has been found that transducersusing DC-lll as a coupling agent have an increase in power output ofabout 3-5 db over transducers using castor oil. This present methodeliminates the time requiredv to mechanically and electrically removecavitated or oil soaked elements. Additionally, the use of the specialheated chisel allows the element faces to be removed from the elementlaminations without any damage to the element faces. Consequently, newelements are not required for normal overhauls. Finally, the presentinventive method eliminates the time required to test castor oil for lowmoisture content. The new method increases the performance in servicetime and reduces reworking time due to poor coupling.

STATEMENTS OF THE OBJECTS OF THE INVENTION The major object of theinvention is to provide a more suitable and efficient method to reclaimold transducer elements. Another object of the invention is to provide amore suitable agent to repair old transducer elements.

' A more particular object of the invention is to provide a betterenergy transfer coupling and seal, thereby making it possible to reclaimold transducers.

Other objects and features will be apparent from the followingdescription of the invention and from the accompanying drawings and flowdiagram of the preferred embodiment of the present inventive methodwherein:

FIG. 1 is a simplified drawing illustrating the modified soldering ironfor stripping the element face plates;

FIG. 2 is a simplified drawing illustrating the boot expander and adetailed showing of the boot curled over the tension bolt;

FIG. 3 is a simplified drawing illustrating the basic transducerelements and the manual application of Compound DC-lll to the transducerelements;

FIG. 4 is a flow diagram of the disclosed method of repairingtransducers; and

FIG. 5 is a simplified drawing illustrating the modified method ofrepairing transducers.

I In order to clearly understand the method of repairing a transducer, adiscussion of the compound used in this method will be presented.

Di-Methyl Polysiloxane Oil Silicone Oxide (SiO2) sold under the tradename Dow Corning 1]] Compound or DC-lll (hereafter referred to asDC-lll), is a stiff, non-melting silicone material that maintains itsconsistency over a temperature range from about 40 to 500 F.

Because of its low volatility, chemical resistance and sealing abilityit is commonly used as a sealant for vacuum and pressure systems and asa sealant and lubricant for chemical processing equipment. Nonoxidizingand non-gumming DC-l 1 l is used in pressure lubricated plug valves,control valves, flow meter bearings and ceramic plug locks. Moreover,because of its outstanding water resistance, it is used to lubricatevalves of water softeners.

Water repellant and chemically resistant, the compound c'an be used as aseal for floating telephone batteries. It also serves as a lastinglubricant for synthetic rubber O-rings and seals in high temperatureapplications. The heavy consistency of the compound can be utilized tokeep the rubber seals in position.

Although not previously used for this purpose, it has been discoveredthat DC-l 11 is extremely suitable for use as an energy couplant insonar transducers and hydroplanes, as well as a repair material for thetransducers if combined with a proper method of application.

Inasmuch as cavitation is the major cause of failure of sonartransducers, it has been found through testing of various compounds thatcompound DC--] 1 1, when properly applied, virtually eliminates thecavitation in most types of transducers.

REPAIR PROCEDURES USING DC-l 11 Referring to FIGS. 1 and 4 of thedrawings the inventive method consists of stripping off all of theneoprene face plates using a heated chisel (step I). A modifiedsoldering iron l has been successfully used and offers a simple methodof face plate removal. The soldering iron used is an American BeautyCatalog No. 3178, which draws 300 watts. The copper tip (2) is modifiedto form a chisel with a steel edge. It should be noted that the steeledge is not essential, however, it greatly extends the life of thechisel. Returning to FIG. 4, after stripping the face plates (step I),it is necessary to clean the exposed laminations with a wire brush (stepII). Next apply DC-l l 1 compound (step III) to all element faces byhand 11 (see FIG. 3). It is most important that the compound be placedover the complete radiating area of each element 11 in a smooth thinlayer without the entrapment of any air bubbles. A fillet of thecompound must be built up at the top and bottom of each element 11 toform a transition between the level of the nickel radiating face 9 andthe level of the plastic separators 10. No attempt need be made to fillinterstave spaces 12 with DC-lll compound.

Referring to FIGS. 2 and 4, (step IV) consists of mounting a clean, dryboot 6 on a boot expander 3. The boot 6 must be mounted on the expander3 so that the boot edge is level with the bottom edges of the expanderbars 4. If this procedure is followed closely, the boot, with expanderbar element still beneath it, will mount on the transducer as shown inFIG. 2 after the tension screws 8 are removed. Referring to FIGS. 4 and5, there is a modification of the recited inventive method in which theboot is coated with DC-l l l on its interior surface (IVa). The bootcoating is applied to the interior surface of the boot by placing DC-l Il (14) over one section of the interior (15) of the boot 10, runningfrom top to bottom and then spreading it throughout the inner surface byplacing the outside surface of the boot on a long, fiat surface 17 androlling it (16) (such as a floor or long table) some distance across theflat surface 17, while the top surface is manually pressed to the bottomsurface, forcing the interior sides to slide against one another. Thisprocedure, when viewed from the side, resembles a collapsed tank treadbeing pushed ahead. Referring to FIG. 4, (step V) consists of using astandard vacuum of 27 inches inside the transducer to secure the boottightly to the radiating surface and holding this vacuum for at least 24hours. The boot should form a shape similar to that shown in FIG. 2. Thesteel bands are applied at the top and bottom areas only; (step VI).Care should be taken so that no bands extend over radiating surfaceareas. Finally, the vacuum is then reduced to the normal operationallevel of the transducer, that is 6 inches of vacuum, (step VII).

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

We claim:

1. The method of repairing old transducers including a transducer withface plates, radiation plates, separation plates, and interstave spacescomprising the steps of:

a. stripping the face plates of said transducer with a heated strippingmeans to expose said radiation plates, separation plates and interstavespaces;

b. cleaning said radiation plates, separation plates and interstavespaces with an abrasive cleaning means;

c. applying a Di-Methyl Polysiloxane Oil SiO2 to the radiation platesand separation plates;

(1. building a layer of Di-Methyl Polysiloxane Oil SiO2 compound at thetop and bottom of said radiation plates to form a transition areabetween said radiation plates and the level of the separation plates;

e. mounting a dry boot over the coated radiation plates and separationplates of said transducer;

f. applying a standard vacuum to secure the boot to the transducer;

g. applying steel boot bands at the top and bottom of the boot; and

h. reducing said standard vacuum to the normal operational vacuum levelof said transducer.

2. The method recited in claim 1 wherein the boot is coated withDi-Methyl Polysiloxane oil SiO2 compound on the interior surface of saidboot.

3. The method recited in claim 2 wherein the boot coating is applied byplacing said Di-Methyl Polysiloxane over one section of the interiorsurface of said boot running from the top to the bottom of said bootinterior and being spread throughout the inner surface of said bootinterior by placing the outside surface of said boot on a flat surface,rolling the boot over said flat surface while pressing and sliding thetop interior surface of said boot to the bottom interior surface of saidboot.

4. The method recited in claim 1 wherein said standard vacuum is 27inches and is applied for approximately 24 hours.

5. The method recited in claim 4 wherein the normal operational vacuumlevel of the transducer is reduced to about 6 inches of vacuum.

2. The method recited in claim 1 wherein the boot is coated withDi-Methyl Polysiloxane oil + SiO2 compound on the interior surface ofsaid boot.
 3. The method recited in claim 2 wherein the boot coating isapplied by placing said Di-Methyl Polysiloxane over one section of theinterior surface of said boot running from the top to the bottom of saidboot interior and being spread throughout the inner surface of said bootinterior by placing the outside surface of said boot on a flat surface,rolling the boot over said flat surface while pressing and sliding thetop interior surface of said boot to the bottom interior surface of saidboot.
 4. The method recited in claim 1 wherein said standard vacuum is27 inches and is applied for approximately 24 hours.
 5. The methodrecited in claim 4 wherein the normal operational vacuum level of thetransducer is reduced to about 6 inches of vacuum.